Biomass feedstock is useful in numerous industries such as the production of cellulosic ethanol, electricity production, feed, heating fuels, and other commercial applications.
The 2005 Billion Ton study by the U.S. Department of Energy and U.S. Department of Agriculture concluded that agricultural and forest based biomass can displace 30% of the U.S. petroleum consumption by using approximately one billion dry tons of biomass feedstock per year.
The Energy Independence and Security Act of 2007 requires the United States to make one billion gallons of cellulosic ethanol from wheat straw, corn stover, rice straw, soybean stubble, milo stubble, forage sorghum, prairie hay, woodchips, cotton-gin residue, and a dozen other forms of agricultural waste and residues. In the past, such waste and residues materials have been generally considered to be of little or no value. In the past, meaningful volumes of cellulosic biomass agriculture material have not been brought to market on a commercial scale due to difficulties in integrating the supply chain to source, harvest, transport, store, and process the material at a profit. Cellulosic ethanol producers and other renewable biomass users like electric utilities and industrial co-generation facilities require reliable supplies of high quality biomass feedstocks. Successful and economic production of biofuels will facilitate independence from fossil and petroleum-based fuels and reduce environmental concerns relating to production, transportation, storage, and use of such fuels; cellulosic ethanol is the only real sustainable transportation liquid fuel. Thus, when correctly pursued, cellulosic ethanol can address many of the issues undermining national security and environmental well-being.
Biomass production from corn, soy, wheat, and other stover has not been practical or economical due to several barriers and risks. The use of crop stover in commercial scale production has been unsuccessful primarily due to (1) cost and logistics of stover (due to the low density of product) delivery for processing; (2) cost of protecting stored stover bales from weather and fire; (3) stover degradation; (4) durability in withstanding standard material handling and transportation; (5) inability to use current material handling/storage infrastructure, resulting in high capital and operating costs; and (6) lack of a proven and reliable grinding shredding and pellet processing system for agriculture waste and residues that works on a mass commercial scale and does not use binding agents or other additives.
The agricultural residue and energy feed stock supply chain is an important component of large scale biofuel production and meaningful electric generation, but it has yet to be established, thereby slowing deployment of cellulosic ethanol production, electrical generation, and other renewable energy technologies. The financial risks associated with feedstock ability to effectively be stored and transported to market and processed on a continuous year-round basis are a significant concern for investors and lenders.
Pelletizing of certain types of agricultural materials is an established practice. These agricultural materials are usually used as animal feed but more recently, some food crops such as hybrid corn, soybean oil, and sugar cane have been used for energy production. Alfalfa is one example of a feed crop that has been pelletized for years. Although it has only been used on a very small scale for fuel pellets, alfalfa has come under fire in the food for fuel debate. These types of feed crops contain protein, starch, sugar, and/or fat that serve as a natural binder in the pelletizing process.
Pelletizing non-food and non-primary feed crop residues has been problematic due to the lack of natural binders. For example, corn stover, soybean stubble, wheat straw, fruit tree trimmings, and walnut shells do not contain substantial protein or starch, which are natural binders. Thus, binder additives have to be used to facilitate pellet formation, which adds costs and creates emission concerns, making agricultural residue pellets undesirable or unfeasible due to environmental issues. Also, pellets made with binders are subject to decomposition and breakdown during normal handling, storage, and transport which decreases the percentage of useful pellets. Agricultural residues have been used as a feed additive due to the fiber content, but they are currently not a primary feed ingredient. Traditional pellet processing uses steam conditioning to pelletize; this reduces yields for liquid fuels producers and results in lower BTU value during combustion. The Applicant's pellet manufacturing process does not use binders or steam conditioning.